1. Field of the Preferred Embodiment(s)
This invention generally relates to a device to mold polymer bonded magnets. More specifically, the invention relates to a tool for variably controlling the orientation of the magnetic particles during molding of polymer bonded magnets.
2. Background of the Invention
Polymer bonded magnets are used in a variety of applications from refrigerator magnets to magnets for use in non-contacting position sensors. In non-contacting position sensors, the magnets need to have a magnetic field strength that varies along at least one dimension of the magnet. This can be done by varying one or more dimensions of the magnet. In other words, the magnet has a slope with a thick end and a thin end. Polymer magnets are molded by injecting a heated polymer containing magnetic particles into a mold. An electromagnet is placed adjacent the mold during molding to orient the magnetic particles in the desired direction of maximum field strength. Molding variable thickness magnets presents its own unique set of problems. It is difficult to mold magnets that have very thin sections. It is desirable to use a constant thickness magnet and impart a variable magnetic field strength to the magnet or to vary the magnetic field strength in sloping magnets without very thin sections.
This and other problems will be solved by the preferred embodiments of the invention.